Check valve for air brakes



Dec. 24, 1935.

G. HouPLAlN V CHECK VALVE FOR AIR BRAKES Filed Feb. 2l, 1934 "sudembodya Patented' Dec. 24, 1935 UNITED STATES CHECK VALVE FOR. AIR BRAKES lGeorges Houplain, Paris, France l Application February 21, 1934, Serial No. '112,356

In France February 18, 1933 6 Claims. (Cl. 303-33) This invention relates to a check valve to be. used in connection with brakes working underI the action of compressed air. i

The apparatus constructed according to the invention is made entirely of metal and aims to confer to the brake with which it is associateda wide range of moderating action as well when braking as whenI unbraking.

An example ofthe construction of a valve according to the invention is shown in the accompanying drawing:

As shown in this drawing, the apparatus comprises three main parts viz: a nrst part, having lthe shape of abell, setv upside down, and designated in the drawing by the numeral l, and

containing the second part, 2, hereinafter called the body, and a third part 3, constituting a cover.

The bell or base I, comprises a pipe connection 4, leading to the main piping of compressed air; y the body 2 comprises two such pipe-connections, the iirst one, 5, communicating with the auxiliary reserve tank, not shown, and the second, 8, leading to the brake cylinder.

Within the-hollow body 2, may reciprocate a piston 1 the under 'part 8 of which is/.shaped as a hollow cylinder, externally screw-threaded and. onto which is screwed a cover 8.,

Within the cylinder 8 can reciprocate'a piston Il, normally pushed upwardlyA vby a coil spring II, against the end I2 of a ,stem I3 which can Near its under part, the stem I3 is provided with two collars I4 land ILbetw'een which is located the plane base of piston 1. Connection is thus established between piston 1 "and hollow stem I3, the latterbeing so as to say the lconnecting rod of the il'r'st. v

At the upper part of stem I3 is situated a piston 28, provided with an aperture 21 enabling a communication to be established between two` spaces or chambers C1 and C: respectively situated on the two faces of said piston 28.

The stem I3 contains a channel 29, terminating atthe top into a duct 80. This duct permits the air contained in chamber b and coming from the auxiliary tank, to enter the braking cylinder through duct 28. The apparatus operates as follows:

The air, coming from the main piping pene.- I

trates in chamber a, passes through the groove e into chamber b and thence, through duct O into the auxiliary tank R-A. When braking is applied, a depression is caused in the main pipe, piston 1 is therefore moved down by superior auxiliary reservoir pressure'present in chamber b, pulling with it the stem I3 and comes to bear. by its peripheral edge 3| against the seat 82. closing thereby the groove e and communication between chamber a and chamber b. As the pressure goes on to decrease, the air from the auxiliary tank acts on the upper face of piston I8, this latter moves therefore down and opens the passage to the air from chamber b into the'brak` ing cylinder, through bore 29 and duct 80.

When the pressure in the auxiliary tank Rf-A 10 has been slightly lowered so as to become equal to the pressure in the main pipe, increased by the action of spring II, the piston lI0 will move up again and close the bore 29.

A repeated depression in the main pipe C. G. lo

will produce the same eifect until pressure balance is attained between the auxiliary tank and the cylinder. l It must'be noticed that air entering the brake cylinder penetrates also in chamber Cz and further, through channel 21 in chamber C1 so that piston 28 is free to move in the closed upper part of chamber Cz. v

In case of emergency braking, the pressure in vthe braking cylinder reaches the value of the pressureprevailing in the auxiliary tank for a single operating action. i,

From the above it is shown and understood that a very fine graduation of braking action is easily obtainable with the apparatus. As concerns the unbraking, if air is led into the main pipe and in chamber a, the pressure will increase in the latter and thereforetlie piston 1 will move upwards;

' if the introduction of air is gently regulated, the

stem I3 will be swiftly moved up by piston 1. As piston' 'I moves up, the stem Il lwill come to bear by its upper end against piston 28 and the duct 21 will therefore be closed; a further action will cause the stem I3 to ralse.\piston 28 against the action of spring 84 and soon stop the displacement of stem I3. But at this timefthe feeding groove e for the auxiliary tank is'slight-ly open and the auxiliary tank can be fed without unbraking. v

Ii' the quantityvof air introduced is suiiicient and therefore alsoy the pressure, the piston 1 will .continue to move 'and the piston 28 will be raised -whilst the air contained in chamber C: will es cape externally through duct' 24.

The unbrakins graduation is therefore quite tem, comprising piston 1 and stem I8 moves up vtank whilst brakes are on.

f tank is much greater (about 40 times) than that of chamber C1.

If then, the pressure in chamber a increases no more, balance is established between the pressures in chambers aand b andthe air acting in chamber C1 on the upper face of piston 2l pushes 4' this piston down and closes the communication from inside of the cylinder to the free by closing ductu. Theaircannomoreescapefromthe brake cylinder where the pressurey is maintained at its full value.

.Ifnow. air isagain sentin the pipe,the piston 1 wilibe movedupandairfrom chamberCawill be able to escape again for the piston 28 has been pushed up from its seat.

It has thus been shown that the apparatus forming the object of thepresent application allows a.: easy graduation of unbraking.

The check valve described shows the properties required from good working brakes, lviz: graduation ability when braking, graduation ability when unbraking. and feeding of the auxiliary I claimz- 1. A check valve for a compressed air brake for controlling the connection between atrain pipe, a brake cylinder and an auxiliary reservoir, comprising a` piston. a housing for said piston, an

axially perforated rod connected to move with said piston, a cylinder element on said piston, a second piston movable in said cylinder element and adapted to close the lower open-end of said rod, a spring urging said second' piston against o, said lower end of said rod, means for applying whereby on ,application of the brake the fall of pressure in the train pipe causes the first piston to move to stop the charging of the auxiliary reset-- -vcir and to draw with it the axially perforated rod, the under end of which is obturated by the second piston until the pressure of the auxiliary reservoir is sufllcient to force down the second piston to open the axial bore of the said rod and allow the introductioneof compressed air to the 5 brake-cylinder; and when the pressure in the auxiliary reservoir becomes equal to that prevailing in the main piping added to the action of the spring acting on the second piston, the latter again rises tovclose the axial bore of the central 0 rod.

3. In a check valve as claimed in claim l, means whereby the charging of the auxiliary reservoir is possible when the brake is applied wherein the said axially perforated rod obturates a duct 15 formed in the center of the third piston when the pressure in the train pipe rises and tends to lift the third piston, such lifting movement being limited by the strength of a spring acting on said third piston so as to permit charging of the aux- 2o Viliary tank whilst limiting suchlifting so that the brake is not released.

4. AIn a check valve as claimed in claim 1, means whereby the release of thel brake'is performedby raising the pressure in the .train pipe tqpro- 25 mote the raising ofy the nrst piston controlling the said rod, the upper end of said rod closing a duct bored in the upper-spring loaded piston and moving the latter to permit release of the pressure in the brake cylinder and exhaust thereof 3o to the free air.

5. A check valve as claimed in claim. 1, further comprising a packing against which the first piston seats .to close communication between the upper and under sides thereof, said communica- 35 tion being eifected by means of a groove, packing on the second piston against which the open end of the perforated rod seats, an enclosing housing for the third piston in which the exhaust port if formed, a bore in said third piston which is enu, gaged by the upper end of said rod, and a spring -in said housing tending to force said piston against the upper end of said rod. f

6. A check valve as claimed in claimfl, wherein said axially perforated rod'is reduced in'dlam- 5 eter towards its upper end and wherein lateral ports formed in said reduced portion are in cornmunication with the perforation in the rod and open intr.` a chamber surrounding said rod and limited at the top by the said third piston, said g@ chamber beingv connected to the brake cylinder by means of a passage. l

' GEORGES VHOUILAIN. 

